Anterior chamber inflammation after the injection of endothelin-1 into the vitreous and the effect of ET A receptor antagonist

Abstract

To assess the receptors which mediate the inflammatory reaction induced by endothelin-1 (ET-1), we investigated the influence of pre-treatment with an ETA receptor antagonist (97-139) on the increase of aqueous protein concentration (APC) after the injection of ET-1 (10(-4), 10(-5)M) into the vitreous cavity of pigmented rabbits. The concentration of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) in the aqueous humor after the injection of 10(-4)M ET-1 with or without pre-treatment with 97-139 (10(-1), 10(-2), 10(-3)M) was also studied. Pre-treatment with 10(-2)M and 10(-1)M 97-139 completely prevented the APC increase induced by 10(-5)M and 10(-4)M ET-1, respectively. Increases in aqueous PGE2 concentration were observed after the injection of ET-1, which was inhibited by pre-treatment with 97-139. Aqueous LTB4 concentration was not changed significantly by ET-1. These results indicate that the effects of ET-1 on APC are at least partially mediated by the cyclooxygenase pathway of arachidonic acid cascade, and that ETA receptors play an important role in these reactions.